Um, not really. Your question is far too general of course for any specific answer. But you cannot just set some flag that tells MATLAB to arbitrarily use old functions that were replaced. That would cause other problems, causing new functionality to now fail, and it would be very difficult to predict the mess that would happen.
You have two simple choices.
- Stay with the old release. As years go by, you will have more and more problems. At some point, that old release will no longer even be supported on your latest computer. Sadly, you are getting pretty close to that point. I'd guess you won't be happy then, but the problem will not be that of MATLAB, but the changes in your computer and OS that no longer will even run that old release. (And yes, I've seen it happen, it does happen, and it will surely continue to happen.)
- Use MATLAB and the tools in it (mainly the debugger) to see where the problems in that old code lie. Figure out what changes need to be made. Change them, so that the code is now updated, and it will run in the new release. This is probably not that big of an issue, because MathWorks tries incredibly hard NOT to make old code obsolete. So there will be relatively few problems that cannot be easily repaired. Yes, this will force you to learn more about MATLAB, and to dig into those old tools. It may even force you to rewite some older tools. Such is life. The good news is you can probably improve some of those old tools too. Look at the bright side!
The advantage of (2) is it will give you code that is now usable into the future. Just bite the bullet and fix the code. It only hurts for a little while.
As well, a god thing is the update will probably be not that difficult, since if you know when your code stopped being forwards compatible, then you just need to look at the release notes for the version that came after. What was changed there? Those notes will also give you some indication of the changes that will be necessary, so you will quickly be able to see how and where you need to fix the old code.
Addendum: I can actually think of two cases where a flag of some sort exists in MATLAB to do something that has been outdated as a feature. The first is when you save a .mat file. That is, the save command/function has a version option, that can sometimes save variables into an older version compliant .mat file. Of course, that will fail if the variables were of a class that did not even exist in the old release. For example, if you tried to save a structure into a release of MATLAB compliant file before MATLAB even had structures? It must then fail.
The second example I can think of is in the gridddata function, where it has a 'V4' option, allowing users to use an old option that still has value, dating back to version 4 of MATLAB. (That was when MATLAB used version numbers to identify their releases, so a long time ago.) There are probably some other flags, etc., that enable backwards capability, but they are not terribly common, nor are they generally necessary.
